Arta's 13th-century walls, erected 10m high by the Byzantine despotate atop ruins of ancient Ambracia, stand on the north side of town. They're perhaps more impressive from the outside than in (just as well, as the gates are not always open). In the 20th century, a government-run Xenia hotel was built in the centre, but it is now a modernist ruin amid overgrown greenery. In the southwest corner, the inner citadel is an outdoor theatre for summer concerts.